What is nuclear fusion?
Nuclear fusion (in this case, we are talking about thermonuclear fusion) is a reaction
According to modern astrophysicalnotions, the main source of energy of the Sun and other stars is thermonuclear fusion occurring in their depths. Under terrestrial conditions, it is carried out with the explosion of a hydrogen bomb. Thermonuclear fusion is accompanied by a colossal energy release per unit mass of reacting substances (about 10 million times more than in chemical reactions). Therefore, it is of great interest to master this process and, on its basis, create a cheap and environmentally friendly source of energy. However, despite the fact that large scientific and technical teams in many developed countries are engaged in research on controlled thermonuclear fusion (CTF), there are still many complex problems to be solved before the industrial production of thermonuclear energy becomes a reality.
Modern nuclear power plants using the processfission, only partially meet the world's electricity needs. Natural radioactive elements uranium and thorium serve as fuel for them, the abundance and reserves of which in nature are very limited; therefore, many countries face the problem of importing them. The main component of fusion fuel is the hydrogen isotope deuterium, which is found in seawater. Its reserves are generally available and very large (the World Ocean covers ~ 71% of the Earth's surface area, and deuterium accounts for about 0.016% of the total number of hydrogen atoms that make up water).
In addition to the availability of fuel, thermonuclear energy sources have the following important advantages over nuclear power plants:
- the CTS reactor contains much less radioactive materials than a nuclear fission reactor, and therefore the consequences of an accidental release of radioactive products are less dangerous;
- thermonuclear reactions generate less long-lived radioactive waste;
- TCB allows direct generation of electricity.
The successful implementation of the fusion reaction depends on the properties of the atomic nuclei used and the possibility of obtaining a dense high-temperature plasma, which is necessary to initiate the reaction.
How is energy released during fusion?
Energy release during nuclear fusion is due toextremely intense forces of attraction acting inside the core; these forces hold together the protons and neutrons that make up the nucleus. They are very intense and decay extremely quickly with distance. In addition to these forces, positively charged protons create electrostatic repulsive forces. The radius of action of electrostatic forces is much greater than that of nuclear forces, so they begin to prevail when the nuclei are removed from each other.
Under normal conditions, the kinetic energy of nucleilight atoms are too small to overcome the electrostatic repulsion, they could approach and enter into a nuclear reaction. However, the repulsion can be overcome by "brute" force, for example, by colliding nuclei with high relative velocity.
Why are scientists doing nuclear fusion?
Researchers developing thermonucleara reactor that can generate more power than it consumes has shown in a series of recent work that their designs must work, restoring optimism that this clean, limitless source of energy will help alleviate the climate crisis.
A group of researchers from MassachusettsInstitute of Technology (MIT) and other institutes declares that the compact fusion reactor SPARC will work in reality. At least in theory, as they claim in a series of recently published studies.
The team points out that during the planning stages nono unexpected obstacles or surprises were found. This is stated in seven articles written by 47 researchers from 12 different scientific institutions.
Although the new reactor is still at an early stagedevelopment stage, scientists hope that by the end of the decade it will be able to start producing electricity. Martin Greenwald, one of the project's senior scientists, told The Guardian that a key motivation for an ambitious timeline is meeting energy needs in a warming environment. “Fusion seems like one of the possible solutions to get out of the impending climate disaster,” he said.
What is the problem with fusion and how can it help the planet?
Nuclear fusion, a physical process thatpowering our sun occurs when atoms collide together at extremely high temperatures and pressures, causing them to release huge amounts of energy by fusing with heavier atoms.
Since it was first discovered in the pastcentury, scientists have sought to use thermonuclear fusion, an extremely dense form of energy, the fuel of which - isotopes of hydrogen - is abundant and replenished. Moreover, fusion does not produce greenhouse gases or carbon and, unlike nuclear fission reactors, carries no risk of melting.
However, the use of this form of nuclear energyproved extremely difficult because it required heating a "soup of subatomic particles" - plasma, to hundreds of millions of degrees - too hot for any container to handle. To get around this, scientists have designed a donut-shaped chamber with a strong magnetic field passing through it, called a tokamak, that holds the plasma in place.
What is already being developed?
Massachusetts Institute of Technology Scientistsand subsidiary Commonwealth Fusion Systems started designing a new reactor, more compact than its predecessors, in early 2018, with construction to begin in the first half of next year. If their schedule goes according to plan, a reactor called Sparc could produce electricity for the grid by 2030, according to researchers and company officials. This will be much faster than the existing major fusion energy initiatives.
Existing reactor designs are too largeand roads to actually generate electricity for consumers. Using state-of-the-art ultra-strong magnets, the MIT and Commonwealth Fusion team hopes to create a compact, efficient and scalable tokamak reactor. “What we really did was combine existing science with new material to open up huge new possibilities,” Greenwald said.
After demonstrating that the Sparc devicecould theoretically produce more energy than is required for operation, in research papers published in September, the next step is to build a reactor and then a pilot plant that will generate electricity on the grid.
All the pros and cons of nuclear fusion
Scientists and entrepreneurs have long promised thatthermonuclear fusion is just around the corner, but faced insurmountable problems. This has caused reluctance to invest in it, especially as wind, solar and other renewable energy sources, although less powerful than fusion, have become more efficient and cost effective.
But the situation is changing.In Biden's $ 2 trillion plan, he called advanced nuclear technology part of a decarbonization strategy. Democrats have supported nuclear power for the first time since 1972. Significant investment is also coming from private sources, including some large oil and gas companies, who see fusion as a better long-term foothold than wind and sun.
According to Bob Mumgaard, executiveDirector of Commonwealth Fusion, the goal is not to use fusion to replace solar and wind power, but to complement them. “There are things that will be difficult to do only with renewable energy sources, on an industrial scale, for example, with the power of large cities or manufacturing,” he said. "This is where fusion comes in handy."
The plasma community as a whole is enthusiastic about Sparc's progress, although some have questioned the ambitious timeline given technical and regulatory hurdles.
Daniel Jessby, 25 years of scientific researchan associate at the Princeton Laboratory of Plasma Physics, is skeptical whether a fusion reactor like the SPARC could ever become a possible alternative energy source. Tritium, one of the isotopes of hydrogen that Sparc will use as a fuel, does not occur in nature and must be produced, he said.
Massachusetts Technological TeamInstitute assumes that this substance will be continuously regenerated by the synthesis reaction itself. But Jessby believes that this will require a huge amount of electricity, making the reactor prohibitively expensive. “When you think that we get solar and wind energy for free, it would be foolish to rely on a fusion reaction,” he concludes.
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